Polishing pads and planarizing machines for mechanical or chemical-mechanical planarization of microelectronic-device substrate assemblies, and methods for making and using such pads and machines

ABSTRACT

Polishing pads used in the manufacturing of microelectronic devices, and apparatuses and methods for making and using such polishing pads. In one aspect of the invention, a polishing pad for planarizing microelectronic-device substrate assemblies has a backing member including a first surface and a second surface, a plurality of pattern elements distributed over the first surface of the backing member, and a hard cover layer over the pattern elements. The pattern elements define a plurality of contour surfaces projecting away from the first surface of the backing member. The cover layer at least substantially conforms to the contour surfaces of the pattern elements to form a plurality of hard nodules projecting away from the first surface of the backing member. The hard nodules define abrasive elements to contact and abrade material from a microelectronic-device substrate assembly. As such, the cover layer defines at least a portion of a planarizing surface of the polishing pad.

TECHNICAL FIELD

The present invention relates to polishing pads for planarizingmicroelectronic-device substrate assemblies, and to methods for makingand using such polishing pads in mechanical and/or chemical-mechanicalplanarization processes.

BACKGROUND OF THE INVENTION

Mechanical and chemical-mechanical planarizing processes (collectively“CMP”) are used in the manufacturing of electronic devices for forming aflat surface on semiconductor wafers, field emission displays and manyother microelectronic-device substrate assemblies. CMP processesgenerally remove material from a substrate assembly to create a highlyplanar surface at a precise elevation in the layers of material on thesubstrate assembly.

FIG. 1 schematically illustrates an existing web-format planarizingmachine 10 for planarizing a substrate assembly 12. The planarizingmachine 10 has a support table 14 with a top panel 16 at a workstationwhere an operative portion (A) of a polishing pad 40 is positioned. Thetop panel 16 is generally a rigid plate to provide a flat, solid surfaceto which a particular section of the polishing pad 40 may be securedduring planarization.

The planarizing machine 10 also has a plurality of rollers to guide,position and hold the polishing pad 40 over the top panel 16. Therollers include a supply roller 20, first and second idler rollers 21 aand 21 b, first and second guide rollers 22 a and 22 b, and a take-uproller 23. The supply roller 20 carries an unused or preoperativeportion of the polishing pad 40, and the take-up roller 23 carries aused or postoperative portion of the polishing pad 40. Additionally, thefirst idler roller 21 a and the first guide roller 22 a stretch thepolishing pad 40 over the top panel 16 to hold the polishing pad 40stationary during operation. A motor (not shown) drives at least one ofthe supply roller 20 and the take-up roller 23 to sequentially advancethe polishing pad 40 across the top panel 16. As such, cleanpreoperative sections of the polishing pad 40 may be quickly substitutedfor used sections to provide a consistent surface for planarizing and/orcleaning the substrate assembly 12.

The web-format planarizing machine 10 also has a carrier assembly 30that controls and protects the substrate assembly 12 duringplanarization. The carrier assembly 30 generally has a substrate holder32 to pick up, hold and release the substrate assembly 12 at appropriatestages of the planarizing cycle. A plurality of nozzles 33 attached tothe substrate holder 32 dispense a planarizing solution 44 onto aplanarizing surface 42 of the polishing pad 40. The carrier assembly 30also generally has a support gantry 34 carrying a drive assembly 35 thattranslates along the gantry 34. The drive assembly 35 generally has anactuator 36, a drive shaft 37 coupled to the actuator 36, and an arm 38projecting from the drive shaft 37. The arm 38 carries the substrateholder 32 via another shaft 39 such that the drive assembly 35 orbitsthe substrate holder 32 about an axis B-B offset from a center point C-Cthe substrate assembly 12.

The polishing pad 40 and the planarizing solution 44 define aplanarizing medium that mechanically and/or chemically-mechanicallyremoves material from the surface of the substrate assembly 12. Theweb-format planarizing machine 10 typically uses a fixed-abrasivepolishing pad in which abrasive particles are fixedly bonded to asuspension material. In fixed-abrasive applications, the planarizingsolution is generally a “clean solution” without abrasive particlesbecause the abrasive particles are fixedly distributed across theplanarizing surface 42 of the polishing pad 40. In other applications,the polishing pad 40 may be a nonabrasive pad composed of a polymericmaterial (e.g., polyurethane), a resin, or other suitable materialswithout abrasive particles. The planarizing solutions 44 used withnonabrasive polishing pads are typically CMP slurries with abrasiveparticles and chemicals to remove material from a substrate.

To planarize the substrate assembly 12 with the planarizing machine 10,the carrier assembly 30 presses the substrate assembly 12 against theplanarizing surface 42 of the polishing pad 40 in the presence of theplanarizing solution 44. The drive assembly 35 then orbits the substrateholder 32 about the offset axis B-B to translate the substrate assembly12 across the planarizing surface 42. As a result, the abrasiveparticles and/or the chemicals in the planarizing medium remove materialfrom the surface of the substrate assembly 12.

CMP processes should consistently and accurately produce a uniformlyplanar surface on the substrate assembly 12 to enable precisefabrication of circuits and photo-patterns. During the fabrication oftransistors, contacts, interconnects and other components, manysubstrate assemblies develop large “step heights” that create a highlytopographic surface across the substrate assembly 12. To enable thefabrication of integrated circuits with high densities of components, itis necessary to produce a highly planar substrate surface at severalstages of processing the substrate assembly 12 because nonplanarsubstrate surfaces significantly increase the difficulty of formingsubmicron features. For example, it is difficult to accurately focusphoto-patterns to within tolerances approaching 0.1 μm on nonplanarsubstrate surfaces because submicron photolithographic equipmentgenerally has a very limited depth of field. Thus, CMP processes areoften used to transform a topographical substrate surface into a highlyuniform, planar substrate surface.

In the competitive semiconductor industry, it is also highly desirableto have a high yield in CMP processes by quickly producing a uniformlyplanar surface at a desired endpoint on a substrate assembly 12. Forexample, when a conductive layer on a substrate assembly 12 isunder-planarized in the formation of contacts or interconnects, many ofthese components may not be electrically isolated from one anotherbecause undesirable portions of the conductive layer may remain on thesubstrate assembly 12 over a dielectric layer. Additionally, when asubstrate assembly 12 is over planarized, components below the desiredendpoint may be damaged or completely destroyed. Thus, to provide a highyield of operable microelectronic devices, CMP processing should quicklyremove material until the desired endpoint is reached.

One technique to improve the performance of CMP processing is to usefixed-abrasive pads (FAPs) with a clean planarizing solution instead ofnonabrasive pads with abrasive slurries. One problem with abrasiveslurries is that the slurry may not uniformly contact the face of asubstrate assembly 12 because the leading edge of the substrate assembly12 wipes the slurry off of the pad 40. As a result, more abrasiveparticles generally contact the edge of the substrate 12 assembly thanthe center, causing a center-to-edge planarizing profile. FAPs seek toresolve this problem by fixedly attaching the abrasive particles to thepad in a desired distribution. By fixing the abrasive particles to thepad instead of suspending the abrasive particles in the slurry, thecenter of the substrate assembly 12 contacts a large number of abrasiveparticles irrespective of the distribution of planarizing solutionbetween the pad and the substrate assembly 12. Using FAPs, however,presents some drawbacks in CMP processing.

One drawback of existing FAPs is that the abrasive particles in the FAPsmay not adequately planarize substrate assemblies with very smallcomponents (e.g., components with a dimension of 0.25 μM or less).Existing FAPs are typically fabricated by covering a Mylar® orpolyurethane backing film with a layer of resin and abrasive particles.The resin is then cured, and the layer of cured resin and abrasiveparticles may be textured. The particle size distribution of theabrasive particles in FAPs should: (1) be consistent from one pad toanother to provide consistent planarizing results; and (2) have smallparticle sizes that are generally less than the critical dimension ofthe smallest components to avoid producing defects and to form a verysmooth surface on the substrate assembly. The particle size distributionin FAPs, however, may not be small enough to planarize very smallcomponents because individual abrasive particles may agglomerate intolarger abrasive elements that have a plurality of individual particles.For example, FAPs may have abrasive particles with individual particlesizes of approximately 10-250 μm, but the individual particles mayagglomerate together to form relatively large abrasive elements in theresin having a size distribution from 0.2-1.5 μm. The formation of suchlarge abrasive elements alters the consistency of the FAPs because theextent that the particles agglomerate varies from one pad to another, oreven within a single pad. Additionally, large abrasive elements mayscratch the substrate assembly and produce defects, or they may damagevery small components of the integrated circuitry on a substrateassembly. Thus, the agglomeration of abrasive particles into largerabrasive elements is a serious problem for fabricating very smallelectronic components with FAPs.

Another drawback of FAPs is that it is difficult to obtain the desireddistribution of abrasive particles in the resin even when the individualabrasive particles do not form a significant number of larger abrasiveelements. For example, it is generally difficult to control thedistribution of the abrasive particles in the resin because the resintypically has a relatively high viscosity that inhibits uniform mixingof the abrasive particles. One particularly difficult application isproducing FAPs with ceria abrasive particles because it is difficult tomanufacture small ceria particles and it is difficult to uniformly mixceria particles in a liquid. Thus, even if the abrasive particles do notagglomerate extensively, it is still difficult to obtain a desireddistribution of abrasive particles at the planarizing surface of an FAP.

Still another concern of using FAPs is that these pads are relativelyexpensive and may wear out rather quickly. FAPs are relatively expensivebecause of the difficulties in obtaining sufficiently small particlesizes and a desired distribution of the abrasive particles, as explainedabove. Moreover, FAPs are subject to wear because the substrate assemblyrubs against the resin at the planarizing surface causing the resin towear down. As a result, some of the abrasive particles may detach fromthe resin and cause defects, or the abrasiveness of the pad may besufficiently altered to produce inconsistent planarizing results.Therefore, using FAPs may increase the costs of planarizingmicroelectronic-device substrate assemblies.

SUMMARY OF THE INVENTION

The present invention is directed toward polishing pads used in themanufacturing of microelectronic devices, and apparatuses and methodsfor making and using such polishing pads. In one aspect of theinvention, a polishing pad for planarizing microelectronic-devicesubstrate assemblies has a backing member including a first surface anda second surface, a plurality of pattern elements distributed over thefirst surface of the backing member, and a hard cover layer over thepattern elements. The pattern elements define a plurality of contoursurfaces projecting away from the first surface of the backing member.The backing member and the pattern elements can accordingly define abase section having a first surface, a plurality of contour surfacesabove the first surface, and a second surface configured to be placed ona planarizing machine.

The cover layer at least substantially conforms to the contour surfacesof the pattern elements to form a plurality of hard nodules projectingaway from the first surface of the backing member. The hard nodulesdefine abrasive elements to contact and abrade material from amicroelectronic-device substrate assembly. As such, the cover layerdefines at least a portion of a planarizing surface of the polishingpad.

The pattern elements are preferably colloidal silica particles that canbe manufactured in precise sizes and shapes. The pattern elementspreferably have particle sizes from approximately 5-500 nm, and morepreferably from approximately 10-120 nm. The cover layer preferably iscomposed of an abrasive layer of material deposited over the patternelements. For example, the abrasive layer can be composed of silicanitride, ceria, silica, alumina, titania, titanium, zirconium ornitride.

In another aspect of the invention, a polishing pad is manufactured bydepositing a plurality of pattern elements over the first surface of thebacking member, and then depositing the hard cover layer over thepattern elements. For example, the pattern elements can be depositedonto the first surface of the backing member by pulling the backingmember through a bath having a liquid and a plurality of the patternelements suspended in the liquid. The pattern elements are preferablycolloidal in the liquid. The backing member is then removed from thebath to evaporate the liquid from the backing member and leave aplurality of the pattern elements distributed over the first surface ofthe backing member. The hard cover layer can then be deposited over thepattern elements using chemical vapor deposition, plasma vapordeposition or other suitable deposition processes for forming thin filmson a surface.

In still another aspect of the invention, a microelectronic-devicesubstrate assembly may be planarized using such a polishing pad bydepositing a planarizing solution onto the polishing pad and pressingthe substrate assembly against the hard nodules at the planarizingsurface. The method continues by moving at least one of the substrateassembly and the polishing pad with respect to the other to rub the faceof the substrate assembly across the nodules in the presence of theplanarizing solution. The hard nodules accordingly abrade material fromthe face of the substrate assembly in a manner similar to abrasiveparticles in a fixed-abrasive pad.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic side elevational view of a web-format planarizingmachine in accordance with the prior art.

FIG. 2 is a partial schematic isometric view of a polishing pad forplanarizing microelectronic-device substrate assemblies in accordancewith one embodiment of the invention.

FIG. 3 is a partial schematic cross-sectional view of a polishing padfor planarizing microelectronic-device substrate assemblies inaccordance with another embodiment of the invention.

FIG. 4 is a partial schematic cross-sectional view of amicroelectronic-device substrate assembly being planarized on thepolishing pad of FIG. 3.

FIG. 5 is a partial schematic cross-sectional view of a stage of amethod for manufacturing a polishing pad in accordance with anembodiment of the invention.

FIG. 6 is a partial schematic cross-sectional view of a stage of amethod for fabricating a polishing pad in accordance with anotherembodiment of the invention.

FIG. 7 is a partial schematic cross-sectional view of another polishingpad for planarizing microelectronic-device substrate assemblies inaccordance with yet another embodiment of the invention.

FIG. 8 is a partial schematic cross-sectional view of another polishingpad for planarizing microelectronic-device substrate assemblies inaccordance with still another embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION

The present disclosure describes polishing pads for planarizingmicroelectronic-device substrate assemblies, methods for making suchpolishing pads, and machines and methods for using such polishing pads.Many specific details of certain embodiments of the invention are setforth in the following description and in FIGS. 2-8 to provide athorough understanding of such embodiments. One skilled in the art,however, will understand that the present invention may have additionalembodiments, or that the invention may be practiced without several ofthe details described in the following description.

FIG. 2 is a partial schematic isometric view of a polishing pad 140 inaccordance with one embodiment of the invention for planarizingmicroelectronic-device substrate assemblies. The polishing pad 140includes a backing member 150 having a first surface 152 and a secondsurface 154, a plurality of pattern elements 160 distributed over thefirst surface 152 of the backing member 150, and a cover layer 170 overthe pattern elements 160 and the backing member 150. As explained inmore detail below, the pattern elements 160 and the cover layer 170operate together to form an abrasive planarizing surface 142 that hascharacteristics similar to fixed-abrasive polishing pads.

In the embodiment of the polishing pad 140 shown in FIG. 2, the patternelements 160 are deposited or otherwise distributed directly on thefirst surface 152 of the backing member 150. The pattern elements 160define a plurality of contour surfaces 162 projecting away from thefirst surface 152. The cover layer 170 is preferably a hard, rigid layerover the pattern elements 160. The cover layer 170 at leastsubstantially conforms to the contour surfaces 162 of the patternelements 160 to form a plurality of hard nodules 172 defining abrasiveelements projecting away from the first surface 152 of the backingmember 150. When the pattern elements 160 are spaced apart from oneanother (as shown in FIG. 2), the cover layer 170 also preferablyconforms to the exposed portions of the first surface 152 to form a lowregion 174 between the hard nodules 172. The pattern elements 160 canalternatively cover the first surface 152 of the backing member 150; inwhich case the cover layer 170 conforms to the contiguous contoursurfaces 162 of the pattern elements. The cover layer 170 accordinglydefines at least a portion of a planarizing surface 142 of the polishingpad 140 for engaging a microelectronic-device substrate assembly duringplanarization. As set forth in more detail below, the materials andconfiguration of the backing member 150, the pattern elements 160 andthe cover layer 170 are selected to provide the desired hardness,abrasiveness and particle distribution for particular CMP applications.

The backing member 150 can be a continuous web for being wrapped arounda roller of a web-format machine, or the backing member 150 can be cutinto a circle for attachment to a platen of a rotary planarizingmachine. The backing member 150 is generally about 0.050 inches thick,but the backing member can have other thicknesses according to theparticular application. In one embodiment, the backing member 150 iscomposed of a compressible polymeric material. Suitable compressiblepolymeric materials include polyurethanes, such as the polyurethanesused in the IC-60 polishing pad, the IC-1000 polishing pad and otherpolishing pads manufactured by Rodel Corporation of Newark, Del. Inanother embodiment, the backing member 150 can be composed of a curedresin to be relatively incompressible. In still another embodiment, thebacking member 150 is composed of Mylar® manufactured by E.I. du Pont deNemours & Co.

The pattern elements 160 can be composed of many different types ofmaterials, and they can have many different sizes and shapes. Suitablematerials for the pattern elements 160 include, at least in part,colloidal silica particles, organic polymers (e.g., latex particles),and/or other types of small particles. The pattern elements arepreferably made from a material that can be manipulated to produce smallparticles that do not readily agglomerate and can be deposited onto thebacking member 150 in a controlled, desired distribution. The patternelements 160 can accordingly be nonabrasive elements or they can beabrasive particles. The pattern elements 160 generally have particlesizes from approximately 5-500 nm, and preferably from approximately10-200 nm, and more preferably from approximately 10-120 nm. The patternelements 160 can also have many different shapes, including sphericalcylindrical, pyramidal or other geometric shapes. In one particularembodiment, the pattern elements 160 are substantially sphericalcolloidal silica particles that have particle sizes of approximately10-120 nm.

The cover layer 170 is preferably composed of a hard material that canabrade the surface of a microelectronic-device substrate assembly duringplanarization. The cover layer 170, for example, can be a thin layercomposed of silica nitride, ceria, silica, alumina, titanium nitride,titania, zirconia or other suitable metallic or ceramic materials. Thecover layer 170 is generally selected to provide the correctabrasiveness to the planarizing surface 142 of the polishing pad 140. Ingeneral, the cover layer 170 is formed by depositing the appropriatematerial using chemical vapor deposition, plasma vapor deposition, orother processes known in the semiconductor fabrication arts for formingthin, conformal layers. The thickness of the cover layer 170 is selectedto provide the desired topography of the nodules 172. For example, whenthe pattern elements 160 have a size of approximately 50-100 nm, thecover layer is approximately 300-600 Å thick.

FIG. 3 is a partial schematic cross-sectional view of a polishing pad240 in accordance with another embodiment of the invention. Thepolishing pad 240 has an intermediate layer 180 between the backingmember 150 and the pattern elements 160. More particularly, theintermediate layer 180 has a lower surface 182 directly on the firstsurface 152 of the backing member 150 and an upper surface 184 over thefirst surface 152. The pattern elements 160 are distributed directly onthe upper surface 184 of the intermediate layer 180 over the firstsurface 152 of the backing member 150. When the pattern elements 160 arespaced apart from one another, the cover layer 170 accordingly conformsto the contour surfaces 162 of the pattern elements 160 and the uppersurface 184 of the intermediate layer 180.

The intermediate layer 180 is preferably composed of a ceramic materialor metal material that provides a hard, rigid support surface for thepattern elements 160 and the cover layer 170. The intermediate layer 180can also be selected from a material that adheres well to the backingmember 150 and the cover layer 170. Suitable materials for theintermediate layer 180 include, at least in part, silica nitride, ceria,silica, alumina, titanium nitride, titania, zirconia or other suitablemetallic or ceramic materials.

FIG. 4 is a partial schematic cross-sectional view of amicroelectronic-device substrate assembly 12 being planarized with thepolishing pad 240 described above with reference to FIG. 3. Thesubstrate assembly 12 can be mounted to a substrate holder 32 similar tothat shown in FIG. 1. The substrate holder 32 presses a front face 13 ofthe substrate assembly 12 against the nodules 172 of the polishing pad240. At least one of the substrate holder 32 or the polishing pad 240moves relative to the other in the plane of the polishing pad 240 tomove the front face 13 of the substrate assembly 12 across the nodules172. More particularly, only the substrate holder 32 preferably moves inapplications using web-format planarizing machines; both the substrateholder 32 and the table move in applications using rotary planarizingmachines. The substrate holder 32 also preferably dispenses aplanarizing solution (see Reference Nos. 33 and 44 of FIG. 1) onto thepolishing pad 240. The polishing pad 240 abrasively removes materialfrom the front face 13 of the substrate assembly 12 because the coverlayer 170 is a hard material and the nodules 172 projecting above thelow regions 174 are effectively very small abrasive particles.Additionally, the chemicals in the planarizing solution can also removematerial from the front face 13 of the substrate assembly 12.

The particular embodiments of the polishing pads 140 and 240 describedabove are expected to be particularly well-suited for planarizingsubstrate assemblies having extremely small components. One aspect ofthe polishing pads 140 and 240 is that the nodules 172 can be very smallabrasive elements composed of materials that are generally difficult tocontrol in particulate form. The nodules 172 can be constructed in verysmall sizes because the pattern elements can be selected from a materialthat: (1) does not readily agglomerate; (2) can be formed in very smallparticle sizes; and (3) can have particles with desired shapes. Thepattern elements 160, for example, can be spherical colloidal silicaparticles. The nodules 172 are also small because the cover layer 170can be a very thin conformal layer of material. The cover layer 170,moreover, can be composed of a desired abrasive material that isnormally subject to agglomerating in particulate form, such as ceria.For example, instead of using ceria abrasive particles that easilyagglomerate and do not provide sufficiently small abrasive particlesizes in a desired distribution on a fixed-abrasive pad, one particularembodiment of the invention uses colloidal silica pattern elements toform a desired pattern of raised features across the backing member andthen covers the silica pattern elements with a thin layer of ceria toform extremely small well-defined ceria abrasive elements. Thus, severalembodiments of the polishing pads provide very small abrasive nodulesthat should be well-suited for planarizing substrate assemblies havingsmall components.

The particular embodiments of the polishing pads 140 and 240 describedabove are also expected to provide wear-resistant pads that have a longoperating life. Existing fixed-abrasive pads are subject to wear becausethe resin binder that holds the abrasive particles may deteriorate orotherwise wear down as the front face of the substrate assembly grindsagainst the abrasive surface and the chemicals in the planarizingsolution react with the resin. Unlike existing fixed-abrasive pads, thehard cover layer 170 preferably completely covers the pads 140 and 240to provide a hard, wear resistant layer across the planarizing surface.The cover layer 170 is expected to be less susceptible to mechanical andchemical wear than the resin binder in existing pads. Therefore,compared to existing fixed-abrasive pads, the embodiments of the pads140 and 240 shown above are expected to have better wearcharacteristics.

The polishing pads in accordance with the invention can be manufacturedaccording to several different methods. FIG. 5 is a schematiccross-sectional view of one stage in a method for manufacturing thepolishing pad 140 (FIG. 2) described above. In this method, the backingmember 150 is drawn through a bath 190 having a fluid 192 and aplurality of the pattern elements 160 dispersed in the fluid 192. Thebath 190, for example, can be contained in a tank 194 having a roller196 and a platform 198. The backing member 150 more particularly, movesthrough the tank 194 and across the platform 198 (arrow Q) to coat thefirst surface 152 of the backing member 150 with a thin layer of thefluid 192 and the pattern elements 160. The fluid 192 then evaporates,leaving a distribution of the pattern elements 160 over the firstsurface 152 of the backing member 150. The distribution and density ofthe pattern elements 160 over the first surface 152 is controlled byselecting the concentration of the pattern elements 160 in the bath 190.After the fluid 192 evaporates from the backing member 150, the coverlayer 170 (FIGS. 2 and 3) is then formed over the backing member 150 andthe pattern elements 160 to create the nodules 172 (FIGS. 2 and 3). Thecover layer 170 is preferably formed by depositing the cover layermaterial using plasma vapor deposition or chemical vapor depositiontechniques known to those skilled in the arts of fabricatingsemiconductor devices.

FIG. 6 is a schematic cross-sectional view illustrating a stage ofanother method for fabricating polishing pads in accordance with theinvention. In this particular embodiment, a nozzle 197 sprays a solution199 onto the first surface 152 of the backing member 150. The solution199 generally contains the fluid 192 and the pattern elements 160.Accordingly, this embodiment also coats the first surface 152 of thebacking member 150 with a layer of the fluid 192 and the patternelements 160. As set forth above, the fluid 192 evaporates from thebacking member 150, leaving a distribution of pattern elements 160 overthe backing member, and then the cover layer 170 is formed over thepattern elements 160 and the backing member 150.

One particular advantage of spraying the solution onto the backingmember 150 is that the distribution of the pattern elements 160 can bevaried in different regions of the polishing pad. For example, a firstsolution having a first concentration and/or a first type of patternelement 160 can be sprayed onto a first region of the backing member150, and a second solution having a second concentration and/or a secondtype of pattern element 160 can be sprayed onto a second region of thebacking member 150. Alternatively, after the liquid of the solution 199evaporates, the nozzle 197 can spray subsequent coatings of solution 199over selected regions of the backing member 150 to add more patternelements 160 to such regions without removing the pattern elements 160previously deposited onto the backing member 150.

The particular embodiments of the methods described above with referenceto FIGS. 5 and 6 are expected to provide a controlled distribution ofvery small particle sizes across the planarizing surface of polishingpads in accordance with the invention. One aspect of these methods isthat the density and/or distribution of the pattern elements 160 overthe first surface 152, of the backing member 150 can be closelycontrolled by selecting the appropriate concentration of the patternelements 160 in the bath 190 or the sprayed solution 199. Additionally,as explained above the particle sizes of the pattern elements 160 can beextremely small. Therefore, several embodiments of methods in accordancewith the invention are expected to provide a controlled distribution ofvery small pattern elements across the surface of the polishing pad.

Another aspect of the methods described above with respect to FIGS. 5and 6 is that they are relatively simple compared to conventionalmethods for forming fixed-abrasive pads. As described above, existingfixed-abrasive pads can be difficult to manufacture because it isdifficult to accurately distribute small abrasive particles in the resinbinder of such pads. In contrast to existing fixed-abrasive pads, thepattern elements 160 are distributed across the backing member 150 bysimply coating the backing member 150 with a layer of pattern elements160 in an evaporable fluid. The abrasive nodules 172 are thenconstructed by forming the abrasive cover layer over the patternelements 160 with processes that are commonly used to form thin films onsubstrates in semiconductor manufacturing arts. Therefore, theembodiments of the methods described above with reference to FIGS. 5 and6 are expected to provide easy and cost effective processes formanufacturing polishing pads in accordance with the invention.

In addition to the polishing pads described above with reference toFIGS. 2-4, there may be other embodiments of polishing pads inaccordance with the invention. For example, FIG. 7 is a schematicpartial cross-sectional view of a polishing pad 340 in accordance withanother embodiment of the invention. The polishing pad 340 is similar tothe polishing pad 240 shown in FIG. 3, and thus like reference numbersrefer to like parts. For example, the polishing pad 340 can include abacking member 150, an intermediate layer 180 directly on the backingmember 150, and a hard cover layer 170 over the intermediate layer 180.The polishing pad 340 also includes a plurality of pattern elements 360that are pyramidal or another type of shape. The pyramidal patternelements 360 are expected to form nodules 372 that have differentabrasive characteristics than the spherical pattern elements 160 shownin FIGS. 2-4. Accordingly, the pattern elements of the polishing pads inaccordance with the invention can be selected to have a shape thatimparts the desired abrasiveness to the polishing pads.

FIG. 8 is a schematic partial cross-sectional view of another polishingpad 440 in accordance with still another embodiment of the invention.The polishing pad 440 is also similar to the polishing pad 240 describedabove with reference to FIG. 3, and thus like reference numbers refer tolike parts. The polishing pad 440 has a plurality of grooves 185 throughthe cover layer 170, the intermediate layer 180 and a portion of thebacking member 150. The grooves 185 can be configured to providechannels for transporting a planarizing solution (not shown) under asubstrate (not shown). The grooves 185 can also be configured to allowthe polishing pad 440 to be flexed (arrow W) so that the polishing pad440 can be wrapped around a roller of a web-format planarizing machine(FIG. 1) without cracking the thin abrasive cover layer 170 or the rigidintermediate layer 180. For example, to provide sufficient flexibilityto a web-format pad, the grooves 185 preferably extend across the widthof the pad normal to a longitudinal axis along the length of the pad.Additionally, the backing member 150 of a web-format pad is preferablycomposed of a flexible material to provide more flexibility for the pad440. The grooves 185 generally have a depth between 2-200 μm, a width ofbetween 20-500 μm, and a pitch (distance between grooves) of between200-1000 μm. In one particular embodiment, the grooves have a depth of20 μm, a width of 100 μm, and a pitch of approximately 400 μm. Thegrooves 185 may also have other dimensions outside of these ranges. Thegrooves 185 are preferably formed by photo-patterning the cover layer170 with a resist, washing a portion of the resist away, and etching thegrooves 185 into the pad 440. Suitable photo-patterning and etchingprocesses are known to those skilled in the art of semiconductorprocessing.

From the foregoing it will be appreciated that, although specificembodiments of the invention have been described herein for purposes ofillustration, various modifications may be made without deviating fromthe spirit and scope of the invention. For example, the backing member150 and any types of features having contour surfaces projecting awayfrom the backing member can define a base section upon which the coverlayer can be formed to construct the nodules. The contour surfaces canaccordingly be features formed from the backing member 150 byphoto-patterning and etching the backing member to form pattern elementsthat are integral with the backing member. As such, the pattern elementsare not necessarily separate particles or other types of features thatare separate from the backing member. Accordingly, the invention is notlimited except as by the appended claims.

1. A polishing pad for planarizing microelectronic-device substrateassemblies, comprising: a backing member having a first surface and asecond surface; a plurality of pattern elements distributed over thefirst surface of the backing member, the pattern elements defining aplurality of contour surfaces projecting away from the first surface ofthe backing member; and a hard cover layer over the pattern elements andover portions of the first surface of the backing member exposed betweenpattern elements, the cover layer at least substantially conforming tothe contour surfaces of the pattern elements to form a plurality of hardnodules projecting away from the first surface of the backing member,the nodules defining at least a portion of a planarizing surface of thepolishing pad for engaging a microelectronic-device substrate assembly.2-83. (canceled)